A method of converting a hydraulic elevator, which is arranged in an elevator shaft, into a drive cable-pulley elevator is known from DE 101 54 171 A1. The known method for modernization relates to hydraulic elevator installations which were, in particular, erected in large numbers in the 1960s and 1970s, since a reliable and relatively economic possibility was made available by these for equipping buildings—even those with just a few floors—with elevator installations in a relatively problem-free manner. After twenty or more year's of operating time a fundamental revision or modernization arises with such hydraulic installations. However, hydraulic elevators have a relatively high energy consumption and need for maintenance and are always susceptible to the risk of escape of hydraulic fluid, which must not pass into the groundwater. Accordingly, for reasons of environmental protection it can be feasible to completely remove the hydraulic elevator and install a drive pulley elevator in place thereof.
The modernization method known from DE 101 54 171 A1 enables conversion of an existing hydraulically actuated elevator installation so that components, particularly the elevator car, remain substantially unchanged and thus the conversion costs can be reduced. In this connection a deflecting cable pulley is installed at the elevator car. In addition, a drive pulley drive unit is arranged in the space available above the car. Moreover, a counterweight is installed. The conveying cables then run from a fixed point at the top in the elevator shaft downwardly to the counterweight, from this back upwardly to the drive pulley drive unit with the drive pulley, around the drive pulley and down again to the deflecting cable pulley at the elevator car, around the deflecting cable pulley of the elevator car and upwardly again to a fixed point at the top in the elevator shaft.
The modernization method known from DE 101 54 171 A1 has the disadvantage that the possibility of use is limited. In particular, the known modernization method is suitable only for so-termed ‘rucksack’ elevators, i.e. for elevator cars having a guide system designed for the purpose of being able to absorb tipping moments arising as a consequence of eccentric suspension. A significant disadvantage of the known modernization method also resides in the fact that the drive arrangement thereof requires a substantial spacing between the ceiling of the elevator shaft and the roof of the elevator car. This results from the fact that between the ceiling of the elevator shaft and the roof of the elevator car a deflecting roller, the drive unit and also the support construction of the drive unit have to be arranged one above the other at the elevator car.